1920, Proof of a postal stationery card with never issued denomination of 20 pfennig, printed in black colour, cancelled "FLENSBURG 14.2.20" and used with long text of the wife of the Swedish commission member Oscar von Sydow, the later Swedish Prime Minister, to the family's nanny in Göteborg, Sweden, showing violet commission cachet on front. A very rare and most unusual item, just 6 postally used proofs have been recorded. This item described in the 'London Philatelist' September 2012 (copy attached). Certificate Gruber BPP (2017)
